Humidity controller



Jan. 12, 1965 P. F. MAGUIRE, JR 3,165,602

HUMIDITY CONTROLLER Filed June 22, 1961 v 2 Sheets-Sheet l FIG. I

mwzzvrok. PHILIP F MAGU|RE,JR.

BY v

ATTOR N EY Jan. 12, 1965 P. F- MAGUIRE, JR 3,165,602

HUMIDITY CONTROLLER Filed June 22, 1961 2 Sheets-Sheet 2 INVENTOR.

PHILIP F. MAGU|RE,JR.

United States Patent 3,165,602 HUMIDITY CONTROLLER Philip F. Maguire,Jr., Providence, R.I., assignor to Grinnell Corporation, Providence,R.I., a corporation of Delaware Filed June 22,1961, Ser. No. 118,906 17Claims. (Cl. 200-41116) The present invention relates to improvements ina control for a humidifying system, and more particularly toimprovements in the linkage between a humidity sensitive element and anactuator for actuating and deactuating apparatus in the system whichadds moisture to the atmosphere in an enclosure.

Certain presently known humidity controllers employ a moisture sensitivemembrane which is exposed to the atmosphere in the enclosure and thelength of which changes substantially linearly with changes in therelative humidity of such atmosphere. Customarily one end of thismembrane is secured to a frame and the other end is connected to alinkage pivoted to the frame and so proportioned and arranged that thechanges in membrane length which are relatively small are greatlymagnified to produce a substantial movement of the actuator connected tothe other end of the linkage. Such magnification is required in devicesof this kind because it is necessary to detect changes in relativehumidity in the order of 1% or less and to actuate or deactuate themoisturizing apparatus by such small changes. It is impractical toemploy membranes of such length that they could accomplish suchactuation and deactuation directly and hence the motion magnificationreferred to above is required.

This motion magnification, however, has the disadvantage that in orderto get substantial motion for a small change in relative humidity itfollows in these previous devices that there tends to be a very largemotion of the actuating part of the linkage when the relative humidityin the enclosure is permitted to change widely from the normallymaintained relative humidity, as for example when the moisturizingapparatus is shut down completely. It is undesirable to permit suchlarge linkage movements because a large protective casing is required toaccommodate them and because they result in excessive strain on themembrane. Accordingly it has been the practice to restrict suchmovements and to interpose a spring between the membrane and the linkageto permit the membrane to change its length after the linkage hasreached its restraining .point without breaking the membrane.

However, in these prior devices these springs have been firm enough andso arranged that they are not substantially deflected by movement of thelinkage prior to the restraint thereof, and it follows that after suchrestraint and because of such deflection these springs imposesignificant and increasing loads on the membranes particularly when themembranes have shrunk considerably after the linkage is so restrained.

Such spring loading of the membrane is harmful to the membrane andpermanently changes its length through stretching so that it is oftennecessary to recalibrate the controller when the controller is again putin operation in order to obtain the desired control.

This problem is solved in the present invention by providing a linkagewhich gives the required motion magnification, in which large motions ofthe actuating end are restrained but in which excessive load on themembrane after restraint is avoided. This solution is achieved in apreferred embodiment of the invention by providing a linkage having atleast two members which, although movable with respect to each otherduring restraint, are held in one relative position with respect to.each other and forced to move together as a unit in that position inresponse to changes in the membrane lengths when the ice linkage is notrestrained; this holding and movement as a unit being accomplished by aforce which has a relationship to relative movement of the members fromthe held position characterized by the force being substantially maximumin the held position and preferably decreasing as the members are movedrelative to each other from such held position. This maximum forcenecessary to so hold the members can be very small because it need onlyovercome such opposing forces as any pull on the linkage by the switchfor the humidifying apparatus, inertia, vibrations and negligible airresistance which might cause relative movement between these parts whenthe linkage is not restrained. When the motion of the membrane is suchthat the linkage reaches its restrained position, the only extra loadplaced on the membrane is that necessary to overcome the above-mentionedslight force holding the parts together for movement as a unit. Itfollows that this slight additional load is not increased by furthermembrane shrinkage and is in fact lessened in a preferred embodiment.

Preferably the two members are pivotally connected to each other and therelative movement comprises pivotal movement with respect to each other.

Other objects and advantages of the invention will become apparent fromthe following description and accompanying drawings which describe andshow for illustrative purposes only certain embodiments of theinvention.

In the drawings:

FIG. 1 is a front elevation view of a humidity control embodying thepresent invention.

FIG. 2 is a partially sectioned side elevation view of the control shownin FIG. 1 taken on line 22.

FIG. 3 is a diagrammatic view of the linkage and switch of FIG. 1illustrating one position of this linkage just prior to movement of themembers relative to each other from their held position.

FIG. 4 is, a view like FIG. 3 illustrating still another position of thelinkage after the linkage has been restrained and the members have beenmoved relative to each other and FIG. 5 is a diagrammatic view ofanother embodiment of the linkage of the present invention.

In the drawings, 2 represents the humidity control having :a frame base4 adapted to be secured to building structure in any convenient mannerfor example by screws 6 which preferably hold the frame base in theupright position shown in 'FIGS. 1 and 2. A frame shelf 8 is secured toframe base 4 by screws 10 and supports through rods 12a conventionaladjustable hook assembly 14 to which is secured through books 16 theupper ends of a pair of conventional humidity sensitive membraneelements '18, e.g. gold-beater skins. The lower ends of these elementsare in turn connected to the hooks 20 adjustably mounted on the upperend of a connector rod 22, which passes loosely through an aperture 24in the shelf 8 and which has its lower end pivotally connected at 25 tothe upper part 26 of a lever assembly 28 made up of such upper part 26and a lower part 30 carried thereon. The pivot 25 is spaced from a mainpivot 32 connecting the lever assembly 28 to the frame through dependingframe shelf lugs 34.

As shown in FIG. 1, the humidity sensitive membrane, connecting rod 22and pivots 25 and 32 are so disposed that a change in the lengths ofelements 18 rotates the lever 28 about the pivot 32.

The lower end of lever part 30 carries a small permanent magnet 36 whichupon such rotation of the lever is moved toward and away from aconventional glass enclosed magnetic switch, sold by McrcoidCorporation, Chicago, Illinois size 983, normally closed. This switch isactuated in one direction when the magnet is close to it and is actuatedin the opposite direction when the magnet is withdrawn. It is mounted onthe frame by a mounting clamp assembly it? and has electrical leads 42leading to a terminal block 44, which is coupled to a humidifyingapparatus (not shown) controlled by the switch. The swing of the lever23 about the pivot 32 as a result of changes in the length of membranes18 causes the lever to move in a plane generally parallel to the planeof the frame base 4 and the mounting assembly 40 locates switch 33generally in this plane adjacent the path of the magnet. A shortening ofthe membrane swings the magnet as clockwise away from the switch 33 anda lengthening of the membrane swings the magnet counterclockwise towardthe switch. If the membrane is lengthening and thereby causing themagnet to move toward the switch, the solid lines in FIG. 1 illustratethe position of the magnet to operate the switch in one direction toturn off the humidifying apparatus. The dot-dash lines 36a in FIG. 1illustrate the position of the magnet to operate the switch in theopposite direction to turn on the humidifying apparatus when the magnetswings away from the switch. It will be noted that the switchdifierential (difference between solid lines 36 and dot-dash lines 36a)is quite small and because the change in length of the membrane ismagnified many times by the linkage it will be apparent that the switch38 will turn the humidification apparatus on and off in response to veryslight changes in membrane length and therefore in response to veryslight changes in relative humidity in the atmosphere.

Preferably, the magnet 36 is prevented from swinging counterclockwisebeyondthe right hand operative position shown in FIG. 1 by an adjustablescrew 64 mounted on the post 52. 7

Because this apparatus is thus made sensitive to very small changes inrelative humidity it necessarily follows that a large decrease inrelative humidity from normal operating relative humidity and thereforea large decrease in'length of membrane 13 will tend to swing the magnet36 far to the left in FIG. 1 about the pivot 32. Since normal operatingrelative humidity is much greater than the natural relative humidity, itfollows that when the humidification equipment is shut down such a largerelative humidity decrease takes place.

It is undersirable to provide a frame which will enclose and protect theparts and which is large enough to accommodate such a larger swing.Furthermore, if the magnet 36 is permitted to swing far to the left theload on the membrane becomes excessive. Consequently, the swing isrestrained by a stop 46 in the path of the lower part 30 of the-lever,which stop comprises a'roller 48 rotatably mounted on a bracket 50 whichis in. turn secured to a forked post 52 extending outwardly from theframe base 4. The lower part 30 extends substantially vertically betweenthe arms of this post, as shown.

The lever 28 is divided into the two lever parts 26 and 30 pivotedtogether at 54 for relative movement with respect to each other topermit the membrane to continue to shorten after the lever part 30engages the stop 46. Part 26 comprises a block 26a having the pivots 25and 32 and further comprises a flat strip having a horizontal portion26b secured to block 26a and extending into a vertical intermediatesection 260, which in turn extends horizontally in the oppositedirection into end section 26d. The end of end section 26d is curveddownwardly and around to form a hinge 58, in which is received a hingepin 60. The ends of the pin are journaled in the arms of a yoke 62extending downwardly from a horizontal top end section 30a of the lowerlever part 30. End section 30a extends along and overlies end section26d and beyond the yoke 62 it extends downwardly into a vertical section30b, which in turn horizontally extends in the same direction intosection 300. On the same side of pivot 54 as the free end of section30a, section 300 turns downwardly into vertical section 30d to the lowerend of which the magnet 36 is secured. Attached to the top of endsection 2nd of the upper lever part and spaced 4 therealong from pivot54 is a permanent magnet 56 having the shape of a round, flat disc.

This magnet $6 normally attracts the free end portion of section 3%(which portion is of a suitable material to provide such attraction)about the pivot 54 aganist the top surface of the magnet in the relativepositions with respect to each other shown in FIG. 1 to thereby normailyhold or lock the lever parts in such relative positions. As a result thelever parts swing together as a unit in response to changes in membranelength overa range having one end defined by the solid line position ofthe magnet 36 in FIG. 1 and having the other end defined by the positionof the magnet 36 in FIG. 3 in which latter position the part 3% engagesstop &6. The lever part 30 is so designed that the force of gravitytends to urge this part clockwise about pivot 54- and to urge the endsection 36a against the top of the magnet 55 to thereby assist themagnet in holding the two lever parts together so they swing together,as aforesaid.

When the lever part 39 engages the stop 46, as shown in FIG. 3,continued shortening of the membranes 18 and consequent swinging of thelever part 26 clockwise about pivot 32 overcomes the magnetic andgravity forces holding or locking the parts together and forces theparts to move relative to each other about the pivot 54, as shown inFIG. 4. At the same time part 30 is carried bodily upwardly by thepivotal connection 54.

Upon subsequent lengthening of the membranes in reand then when the endsection 30a approaches closely to the magnet 56 it takes place becauseof the force of the magnet in addition to the force of gravity.

The combined forces of the magnet 56 and gravity are sufficient to keepthe lever parts 26 and 30 locked together as shown in FIGS. 1 and 3while the magnet 36 is moving through the range referred to. Thesecombined forces need not be very great because the opposing forcestending to disrupt the lock, e.g. vibration, inertia, magnetic pull ofthe switch, etc. are very small. These combined forces shouldprefer-ably not be too much greater than the disrupting forces (takinginto account a safety factor) because the greater the combined forcesthe greater the load on the membrane to unlock the lever parts.

It is a feature of the invention that the locking or holding forcesexerted by the magnet and by gravity are characterized by the fact thatthey do not substantially increase, and preferably decrease, withrelative motion of the lever parts from their locked positions.Consequently, the maximum holding force is applied when the lever partsare in their locked positions, i.e. when relative movement between theparts is zero. The holding force exerted by the magnet decreases withsuch relative movement.

If desired, the total holding force may be supplied by the force ofgravity tending to rotate the part 30 about pivot 54 to locked positionwith respect to the part 26. For example, in such case the disc 56 isnot magnetized and functions only as a spacer. However, it may bedesirable to balance any extra weight of the lower part 30 which isneeded to provide a more stable lock by a counterweight on the upperpart 26 on the opposite side of the pivot 32. In this way the extraweight does not increase the load on the membrane.

Also it is within the scope of this invention to utilize a tensionspring 66, as shown diagrammatically in FIG. 5, between the pivotedlever parts 26' and 30' so arranged that the spring force momentdecreases with the relative rotation of the arm parts from their lockedpositions shown in FIG. 5. This is accomplished by connecting the springbetween the parts so that the effective moment arm of the spring aboutthe pivot 54 decreases as the spring force increases and so that theproduct (moment) of the effective arm and spring deflection decreaseswith relative movement of the parts from their locked positions.

Where the force of gravity is used for locking there may not be anysignificant change in the locking force when the lever parts moverelative to each other as compared to when they are locked together. Insuch case the holding or locking force is still considered to besubstantially-maximum when the lever parts are locked together eventhough, as aforesaid, such force may not decrease appreciably when theparts are moved relative to each other away from lock positions.

It is a feature of the embodiment of the invention shown in FIGS. 1 to 4to provide means for imparting subtantially vertical movement (in thedirection of the longitudinal major axis of the humidifier) to theactuating magnet 36 over at least a substantial part of the entire rangeof movement of the membrane. In FIGS. 1 to 4 this vertical movement isthe vertical movement of magnet 36 after the arm 30 engages the stop 46.Such movement reduces the required overall lateral dimension of thehumidifier (minor axis of the humidifier) and at the same time permitsmagnification of the movement of the membrane. Although such movementhas a slight lateral directional component the major directionalcomponent thereof is in the direction of the longitudinal major axis ofthe humidifier.

The arrangement shown in FIGS. 1 to 4 has the advantage that duringunlocking of the lever parts substantial movement of the area of endsection 30a away from magnet 56, which section is normally held tomagnet 56 when the lever parts are locked, commences at the right end ofsuch area (as viewed in the drawing) and gradually works its way to theleft toward pivot 54 until the Whole area moves a distance from themagnet at which the magnet no longer exerts a substantial pull onsection 30a. This decreases the force necessary at any instant to movethe end section 30a and magnet 56 away from each other and hence reducesthe load on the membranes as compared to moving the whole of theabove-mentioned area away from the magnet by the same amount at the sametime.

I claim:

1. In a humidity control, a linkage for transmitting movement of ahumidity sensitive element to movement of an actuator, said linkagecomprising at least two lever members movable relative to each other,means for applying a force to at least one of said lever members to holdsaid members against relative movement with respect to each other over apredetermined operating range of movement of said element whereby theymove together as a coupled unit over said range, stop means responsiveto further movement of said element beyond said predetermined range forexerting a force on at least one of said lever members to break saidholding force and move said members relative to each other against saidholding force without substantially increasing said holding force,whereby said moving force need only slightly exceed said holding force.

2. A humidity control according to claim 1, said means for applying saidholding force comprising a magnet.

3. A humidity control according to claim 1, said members being soarranged that the force of gravity comprises at least a part of saidholding force.

4. In a humidity control, a linkage for transmitting movement of ahumidity sensitive element to movement of an actuator, said linkagecomprising at least two members movable relative to each other, saidmembers having oppositely facing overlapping sections extending alongeach other and hinged together at one part by hinge means, means forapplying a force to at least one of said members to hold said membersagainst relative movement with respect to each other over apredetermined operating range of movement of said element whereby theymove together as a coupled unit over said range, said holding forceurging another of said sections spaced from said hinge means toward eachother about said hinge means to hold the sections against relativemovement with respect to each other over saidrange of movement, meansresponsive to further movement of said element beyond said predeterminedrange for exerting a force on at least one of said members to move saidmembers relative to each other against said holding force withoutsubstantially increasing said holding force, said moving force forcingsaid other parts of said section away from each other about said hingemeans.

5. A humidity control according to claim 4 in which one of said membersis pivotally attached to a frame at one point and to said element atanother point spaced from said first point for swinging movement aboutthe frame pivot in response to movement of said element, the othermember being supported on said one member for swinging movement togetheras a coupled unit with said one member over said predetermined range.

6. In a humidity control, a linkage for transmitting movement of ahumidity sensitive elementto movement of an actuator, said linkagecomprising at least two lever members movable relative to each other,means for applying a force to at least one of said lever members to holdsaid lever members against relative movement with respect to each otherwhereby they move together as a unit over a predetermined operatingrange of movement of said element, said force having a relationship torelative movement of said lever members with respect to each othercharacterized by maximum force at zero relative movement, stop meansresponsive to further movement of said element beyond said predeterminedrange of movement for exerting a force on at least one of said levermembers to control said means for applying a holding force and move saidlever members relative to each other against said holding force.

7. In a humidity control comprising a humidity sensitive element, aswitch, a lever arm pivotally connected to a frame at one end portionand to said element at an intermediate portion and having a switchactuator at its other end portion swingable towards and away from switchactuating position by swinging movement of said lever about its pivotalconnection with the frame in response to movement of said element, theimprovement comprising dividing said lever into at least two leverparts, means for urging said parts into locking relationship with eachother so that they move together as a unit over a range of movement ofsaid element and means for automatically forcing said parts out oflocking relationship with each other against the force urging them intolocking relationship and for forcing the parts to move relative to eachother without substantially increasing said last-mentioned force inresponse to further movement of said element beyond an end of said rangeof movement.

8. In a humidity control having a frame a linkage for transmitting themovement of a humidity sensitive element to movement of an actuator,said linkage comprising first a lever part pivotally connected to saidframe by a first pivotal connection, a connector pivotally connected toa portion of said lever part spaced from said first pivotal connectionand to said element for rocking said lever part about said first pivotalconnection in response to said movement of said element, a second leverpart, cooperating means on said first and second lever parts, andincluding a second pivotal connection therebetween, for supporting saidsecond part on said first part for swinging movement together as a unitabout said first pivotal connection over a predetermined range of swingof said first part about said first pivotal connection and for pivotalmovement with respect to each other about said second pivotal connectionupon further swinging movement of said first part about said firstpivotal connection.

9. A humidity control according to claim 8, including means for stoppingfurther swinging movement of said second part with said first parttogether as a unit when the end of said predetermined range has beenreached, whereupon said further swinging movement of said first partabout said first pivotal connection forces said first and second partsto move relative to each other about said second pivotal connection andsaid second part to move bodily with said second pivotal connection bywhich it is supported on said first part.

10. A control according to claim 9, said parts having adjacent endsections whichextend in opposite directions from the remainder of theparts along each other in spaced oppositely facing relationship witheach other, said end section of said'second part overlying and beingsupported by the end section of said first part, a portion of one ofsaid opposed end sections spaced from the free end thereof beingpivotally connected to the free end portion of the other end section'toform said second pivotal connection therebetween, means for urgingoppositely facing portions of said end seconds spaced'from said secondpivotal connection toward each other to hold said sections together formovement as a unit during movement of said first part through saidpredetermined range.

11. A control according to claim '10, said means for stopping furtherswinging movement of said second part comprising a stop attached to saidframe and located so that it is engaged by said second part at the endof said predetermined range of swing, whereby further swing of saidfirst part forces. said oppositely facing portions of said end sectionsto move away from each other about said second pivotal connectionagainst the force urging said portions toward each other.

12. A control according to claim 11, said parts being so arranged thatsaid oppositely facing portions of said end sections are urged toward'each other about said second pivotal connection by the force ofgravity, whereby said force of gravity comprises at least a part of saidmeans for urging said oppositely facing end sections toward each other.

13. A control according to claim 11, said means for urging saidoppositely facing portions of said end sections toward each othercomprising a magnet.

14. A control according to claim 11, said end sections being horizontal.

15. A control according to claim 14, the end section of said first partextending from the end thereof opposite the pivoted end portion into anintermediate, upwardly extending vertical section which in turn extendsinto a second horizontal end section, said last-mentioned horizontal endsection extending from the intermediate vertical section in a directionopposite from the direction in which said first end section of saidfirst part extends, the free end part of said second end section beingpivotally connected to said frame to form said first pivotal connection.

16. A control according to claim 15, said end section of said secondpart being generally horizontal and comprising a top horizontal leg of agenerally C-shaped portion of said second part, said G-shaped portioncomprising in addition to said horizontal end section, a verticalsection which extends downwardly from said end section to form the baseof the C and then horizontally in the same direction as said end sectionand beyond said second pivotal connection into the other leg of the Cwhich in turn extends downwardly through'a yoke attached to the frameinto a vertical leg, a magnet at the lower end of said leg for actuatinga mercury switch when it is brought in close proximity thereto.

17. A control according to claim 16, the free end of said first endsection of said first part extending downwardly in and around into ahinge forming a portion of said second pivotal connection, a lug in theform of a yoke extending downwardly from a portion of said end sectionof said second part which is spaced from the free end thereof and islocated at the end portion thereof from which the vertical leg of the 0portion extends to provide bearings for a pin received in said hinge tothereby form said second pivotal connection between said end sections,said second pivotal connection being spaced below the plane of said endsections and holding the end section of the second part spaced above theend section of the first part.

References Cited in the file of this patent 1 UNITED STATES PATENTS1,956,795 Henning May 1, 1934 1,966,931 Mills July 17, 1934 2,897,304Kjellman et al. July 28, 1959 2,974,209 McMichael Mar. 7, 1961

1. IN A HUMIDITY CONTROL, A LINKAGE FOR TRANSMITTING MOVEMENT OF AHUMIDITY SENSITIVE ELEMENT TO MOVEMENT OF AN ACTUATOR, SAID LINKAGECOMPRISING AT LEAST TWO LEVER MEMBERS MOVABLE RELATIVE TO EACH OTHER,MEANS FOR APPLYING A FORCE TO AT LEAST ONE OF SAID LEVER MEMBERS TO HOLDSAID MEMBERS AGAINST RELATIVE MOVEMENT WITH RESPECT TO EACH OTHER OVER APREDETERMINED OPERATING RANGE OF MOVEMENT OF SAID ELEMENT WHEREBY THEYMOVE TOGETHER AS A COUPLED UNIT OVER SAID RANGE, STOP MEANS RESPONSIVETO FURTHER MOVEMENT OF SAID ELEMENT BEYOND SAID PREDETERMINED RANGE FOREXERTING A FORCE ON AT LEAST ONE OF SAID LEVER MEMBERS TO BREAK SAIDHOLDING FORCE AND MOVE SAID MEMBERS RELATIVE TO EACH OTHER AGAINST SAIDHOLDING FORCE WITHOUT SUBSTANTIALLY INCREASING SAID HOLDING FORCE,WHEREBY SAID MOVING FORCE NEED ONLY SLIGHTLY EXCEED SAID HOLDING FORCE.